Closures, more especially for containers



June 15, 1965 G. E. JOWETT 3,189,208

CLOSURES, MORE ESPECIALLY FOR CONTAINERS Filed March 16 1964' Inven+orG. E. JowETT M'oi'neys United v. States Patent 0 3,189,268 CLUSURES,MURE ESPEHALLY FGR (IQNTAlNl-ERS George Edward .ioweit, ll llumbles,Fawansea, Glamorgan,

Wales, assignor to Viscose Beveloprnent Company Limited, London,England, a British company Filed Mar. to, wed, er. No. 352,22ll Claimspriority, application Great Britain, Mar. 19, 1963, 10,884/ 63 4(Ilaims. (El. Zl5-38) This invention concerns improvements in andrelating to closures, more especially for containers.

It has been proposed to form so-called secondary closures for bottlesand the like from synthetic plastics tubing which has been stretched insuch a manner that it can be caused to shrink by heating it to anelevated temperature. The proposed method of applying such closures isto cut the tubing into conveniently short lengths, to place theselengths of tubing over the necks of bottles which have been closed bystoppers orthe like and then to subect the neck ot" the bottle to heatso that the tubing shrinks The present invention provides a shapedstructure for the production in situ of a closure for a container, saidstructure consisting of a tube of heat-shrinkable thermoplastic materialwhich has been heat sealed at one end, and being of such dimensions inrelation to the container to be closed thereby that it can be placedover an opening of the container and shrunk by heat to conform to theoutline of the container. The structure according to the invention hasthe advantage that it provides a complete closure for a container suchas a bottle, being capable of extending continuously over the top of thecontainer. It is also inexpensive and surprisingly neat in appearancewhen shrunk into place. It may be used as a secondary closure, or mayitself form a primary closure, if necessary being provided with an innersealing wad. It may also be used as a primary closure for means otherthan containers, for example as a temporary closure for apertures inmachines, engineering components and the like.

Preferably the heat sealed end of the structure is generally concavetowards the interior thereof. The heat seal may, for example, extend inthe form of a curved line across the end of the tube, said line having aradius of curvature which is smaller towards the ends than in themiddle. By this means a greater neatness in the appearance of thefinished closure may be obtained.

Advantageously the structure is of such thickness and rigidity that whenapplied to a container of which the said outline is in the form of ascrew thread, and shrunk thereon, it can be removed from the containerby an unscrewing movement and subsequently replaced thereon as required.It can thus form a simple and inexpensive screw cap useful as a primaryclosure, In a modified dorm this structure may comprise a ring with opentop capable of forming a closure with a cap, wad or the like and beingremoveable and replaceable as specified. If desired the structure mayhave a skirt portion divided by a line of weakness from a main closureportion. When the structure is applied to a screw threaded container ofsuitable configuration, the arrangement can then be such that the skirtportion is held by a corresponding portion of the container againstrotation with the main closure portion when the latter is unscrewed fromthe container so that the skirt portion is parted from the cloto fitclosely over the bottle and the stopper or primary sure portion andremains on the container. Thus an indication may be obtained that theclosure portion has been removed. The skirt portion can alternatively besecured in position by means of adhesive. a The invention is illustratedby way of example in the accompanying drawings, in which:

FIG. 1 is an elevation of a shaped structure according to the inventionbefore it has been applied to a container, FIG. 2 is a sectionalelevation of a threaded bottle neck with a closure formed by means of ashaped structure as shown in FIG. 1, and FIG. 3 is a plan viewcorresponding to FIG. 2.

Referring to FIG. 1 of the drawings a shaped structure 1 for applicationto a bottle neck having an external diameter of approximately 1% inchesisfcrmed from 2" Wide flat tubing of thermoplastic material which hasbeen molecularly orientated by internal information under the influenceofheat, and subsequently cooled to re, tain it at the inflateddimension. The tubing thus has the property of being heat-shrinkable,that is to say that when heated it will tend to to inflation.

heat seal extending in a curve concave towards the interior of the tube.The curve comprises a central arcua ate portion a which has a centre ofcurvature at a point P on the central axis of the fiat tube, and aradius of curvature of 2 /2 inches, and two symmetrical arcuate endportions b having centres of curvature Q on the radii to the ends of theare a, and radii of curvature of 1 inch each. The are a extends over anangle of approximately 25.

The structure is open at the lower end, and has a lower skirt portion 3,which is partially separated from the body of the structure by a line ofperforations 4.

In order to apply the structure to a container as a closure, it isopened out at the lower end, placed over the open mouth of the containerand then subjected to heat so that it shrinks to conform to the closure.

As shown in FIGS. 2 and 3 the structure hasbeen applied in this mannerto a threaded bottle neck 5. The structure thus takes the form of a cap,beneath which a sealing wad 6 has been applied to the mouth of thebottle. Owing to the shape of the heat sealed end 2 of the structure,this end has now shrunk to conform closely to the flat sealing wad 6,while the remainder of the structure has the same shape as the profileof the bottleneck. As shown, the perforations 4 are located adjacent thelower terminus of the threaded portion 5a of the bottle neck, so thatthe skirt portion 3 is located on an unthreaded portion 5b of the neck.The portion 5!) is provided with radial pips 7 to prevent the skirtportion 3 from turning relatively thereto. If desired, the: pips 7 maybe dispensed with and the skirt portion 3 secured by means of anadhesive.

If the structure 1 is formed of material of sufiicient thickness andrigidity, it can be removed together with the sealing wad 6 from thebottle neck 5, by unscrewing in the manner of a normal screw cap. Inthis operation, the skirt portion 3 will remain on the bottle neck,being (separated from the structure 1 at the line of weakness formed bythe perforations 4. The structure can then be replaced on the bottle asdesired, the separated skirt 3 serving as an indication that it has oncebeen removed.

According to a modification of the above embodiment of the invention,the structure 1 may be applied to the bottle neck 5 in the form of aring instead of a cap, the closure in its final form would then besimilar to that shown in FIG. 2 except that instead of extending fullyover the top of the sealing wad 6 the structure 1 would terminate in theform of an inturned flange extending to the dotted lines X.

return to its dimension prior.

Suitable material for the structure 1 of the above described embodimentsis polystyrene tubing of 0.01 inch thickness (or 0.02 inch when foldedfiat to form a double Wall), which has been inflated during orientationat a blow ratio of 5:1, that is to say the inflated tube has a diameterwhich is 5 times the diameter of the tube before inflation. Thismaterial is convenient to handle during formation of the shapedstructure of FIG. 1, while still having a sufiicient measure ofstability to allow it to be removed and replaced on the screw top bottlein the manner described.

According to a further modification of the above embodiment of theinvention, the structure 11 may be adapted for use as a secondaryclosure or a disposable primary closure, more especially for a containerof other than threaded form. In this case the structure is not providedwith perforations 4, and may be made of less rigid material, for examplepolystyrene of less wall thickness, or polyvinyl chloride.Advantageously, using the same profile of the heat sealed end, thematerial is polystyrene of 0.006" double wall thickness.

Shaped structures as described above may be formed in a continuousoperation from fiat heat shrinkable tubing by heat sealing the tube inconventional manner, using a shaped heated bar, and simultaneouslycutting the tube by means of separate cutter blades. It is important,however, that the time and pressure of application of the bar to thematerial of the structure, and also the tem perature of the bar, shouldbe carefully controlled to avoid substantial shrinkage of the materialduring the heat sealing operation. For example when sealing polystyrenehaving a double wall thickness of between 0.003 and 0.020 inch, the barshould have a temperature of 130 C.-150 C., the pressure per inch of thebar should be from 60-120 lbs. and the time of contact should be lessthan 0.1 second. Equivalent figures for polyvinyl chloride are:temperature 180 C.-210 0; pressure per inch of bar, 60l20 lbs.; timeless than 0.3 second.

The material of the structure adjacent the seal may be cooled, ifdesired, by means of an air blast, suitable shielding then beinginterposed between the air blast and the heat bar. The material of thetube is preferably supported on a resilient base during heat sealingthereof.

I claim:

1. A shaped structure for the production in situ of a closure for acontainer, said structure consisting of a length of heat-shrinkablethermoplastic tubing in flat form and closed at one end by means of aline heat-seal extending across the full width of the fiat tubing, thetubing being of such transverse dimension in relation to the containerto be closed that the said structure can be placed over an opening ofthe container and shrunk to fit the same, and the profile of the heatsealed end of the tubing being generally concave towards the interiorthereof so that when the structure is so shrunk the closed end thereofwill conform to the outline of the container.

2. A shaped structure as claimed in claim 1, in which the profile of theheat sealed end has a radius of curvature which is smaller towards theends than in the middle.

3. A shaped structure as claimed in claim it of such thickness andrigidity that when applied to a container of which the said outline isin the form of a screw thread, and shrunk thereon, it can be removedfrom the container by an unscrewing movement and subsequently replacedthereon as required.

4. A shaped structure for the production in situ of a closure for acontainer, said structure consisting of a length of heat shrinkablethermoplastic tubing in flat form and closed at one end by means of aline heat seal extending across the full width of the tubing, theprofile of the heat seal being concave towards the interior of thetubing so that when the structure is placed over an opening in thecontainer and shrunk to fit the same the closed end of the structurewill present a substantially flat surface extending over said opening, aline of weakness extending across the Width of the tubing to define, atthe open end of the tubing, a skirt portion partially divided from themain closure portion, and the tubing being of such thickness andrigidity that, when the container is provided at said opening with ascrew threaded upper neck portion and an irregular lower neck portion,the main closure portion of the shrunk-on structure can be removed fromsaid upper neck portion by an unscrewing movement and subsequentlyreplaced, while the skirt portion will part from the main closureportion rather than be removed from said lower neck portion.

References Cited by the Examiner UNITED STATES PATENTS 2,328,845 9/43Pike et al. 2l5---38 2,331,794 10/43 Mallory 21538 2,790,286 4/57 Snyder21538 2,954,139 9/60 Owens 21538 GEORGE O. RALSTON, Primary Examiner.

FRANKLIN T. GARRETT, Examiner.

1. A SHAPED STRUCTURE FOR THE PRODUCTION IN SITU OF A CLOSURE FOR ACONTAINER, SAID STRUCTURE CONSISTING OF A LENGTH OF HEAT-SHRINKABLETHERMOPLASTIC TUBING IN FLAT FORM AND CLOSED AT ONE END BY MEANS OF ALINE HEAT-SEAL EXTENDING ACROSS THE FULL WIDTH OF THE FLAT TUBING, THETUBING BEING OF SUCH TRANSVERSE DIMENSION IN RELATION TO THE CONTAINERTO BE CLOSED THAT THE SAID STRUCTURE CAN BE PLACED ONVER AN OPENING OFTHE CONTAINER AND SHRUNK TO FIT THE SAME, AND THE PROFILE OF THE HEATSEALED END OF THE TUBING BEING GENERALLY CONCAVE TOWARDS THE INTERIORTHEREOF SO THAT WHEN THE STRUCTURE IS SO SHRUNK THE CLOSED END THEREOFWILL CONFORM TO THE OUTLINE OF THE CONTAINER.